1. Field of the Invention
The present invention relates to an XY plotter for use for recording images and characters, and particularly relates to the structure of a recording paper feeding portion in the XY plotter.
2. Description of the Prior Art
As well known, in an XY plotter for use, for example, for recording character information or graphic information in a computer or the like, recording paper is fed in one direction by grip rollers and pinch rollers for grasping the recording paper, and recording is performed on the recording paper by use of a recording pen supported by a pen carriage movable in the direction perpendicular to the feeding direction of the recording paper.
In such a conventional recording paper feeding portion of the XY plotter, however, variously sized sheets of recording paper are used. Therefore, an elongated rod-like grip roller to be driven by a driving source such as a pulse motor or the like is provided in the direction perpendicular to the feeding direction of the recording paper, and a pinch roller which is detachable from the circumferential surface of the grip roller is positionally adjustably attached to a fixing portion of the the apparatus. In another case, a grip roller shaft is provided in place of the elongated grip roller, and partial grip rollers are mounted on the grip roller shaft at a plurality of portions thereof in its longitudinal direction. The position of the pinch roller is changed in accordance with the size of recording paper to be used so that one portion of the recording paper is grasped by the partial grip rollers and the pinch roller so as to accurately feed the recording paper. In the former structure, however, there is a problem in the situation where an elongated grip roller having a considerably large mass is used so that the inertia mass of the grip roller is so large that the recently increased demand for rapid feeding of the recording sheet cannot be sufficiently realized. In the latter structure, although the whole inertia efficiency becomes smaller than that of the former structure, there is a problem in that if the number of kinds of the size of recording paper to be used becomes large, it is necessary to mount a number of partial grip rollers onto the grip roller shaft, so that the inertia efficiency of the movable portions cannot be reduced as desired, and it is impossible to handle recording paper having modified sizes.